Electronic imaging systems have been developed which generate pictorial representations in digital form, using a digital camera or a digitizing scanner, for example, or using a computerized "virtual reality" generator. Typically, an image is represented by an array of a large number of "pixels" for which numerical parameter values are provided. In the case of black-and-white images, a single numerical value is sufficient per pixel, indicating brightness. For color images, three parameters are used, e.g. for levels of red, green and blue, or hue, saturation and intensity.
Digital image representation is advantageous in that such representations can be reproduced without loss, so that there is no degradation of image quality in copying. Also, digital images can be readily transmitted over high-speed data channels, and they can be processed by computerized techniques, e.g. for color correction, for manipulation as by "morphing", and for combining multiple images into a composite panoramic view. Panoramic views, obtained as a composite or otherwise, are of considerable importance to tourism, for example.
In pictorial views such as panoramic views, it is often desirable to annotate prominent features with identifying or characterizing information. For example, in a view of a mountain range, identifying information may be desired for prominent mountain peaks and other features at the horizon.